The distribution and size of atheromatous debris after angioplasty with the Kensey catheter was determined after recanalization of 18 segments of human cadaveric superficial femoral arteries (SFA). The debris produced was studied cytologically and measured semiquantitatively. Nearly 80% of all particles ranged from 5 to 15 microns, approximately the size of red blood cells. More than 20% of all particles exceeded this size and 2% were larger than 100 microns. The use of the Kensey catheter dynamic angioplasty system in the lower extremities contains the risk of embolic complications because more than 20% of all particles are larger than human blood cells. Seven patients with occlusion and 3 with stenoses of the SFA were treated with the Kensey catheter system. Recanalization was successful in all and in 1 case, small emboli in the anterior tibial artery were observed. There was a 50% restenosis/reocclusion rate between 2 weeks and 10 months.